Transport officials have been quoted saying up to 40 services have been disrupted as a result of the protest.

The demonstrators say they are supporting the Unite bus workers’ demand for a £500 bonus for the expected extra workload during the Olympic Games.

Unite yesterday called on the 21 operators and the transport agency, TfL, to take part in further talks on Monday at the conciliation service Acas, to try to resolve the dispute.

The depots are all operated by the three bus companies – Arriva, Go-Ahead and Metroline – which secured a High Court injunction preventing some 4,000 workers from taking part in last Friday’s 24 hour strike.

It comes after activists also leafleted at the home in Middlesex yesterday of the director of one of the three operators and at the official opening of the cross-Thames cable car.

Most transport workers in the capital have already secured bonuses worth between £500 and £900.